NAA is one of the most sensitive analytical techniques in existence making possible the study of very small samples. (For example, the minimum analyzable sizes for obsidian and pottery are about 5 mg and 50 mg respectively.) However, due to possible heterogeneity in certain types of archaeological samples, one is advised to supply sufficient sample material such that the chemical analysis is more representative of the whole specimen.
As a general guideline, for the listed sample types we recommend submitting the following minimum amounts:
|Sample Type||Recommended Minimum Size|
2-g potsherd with typically 3–4 cm² of sample area is highly recommended. A sherd with 1 cm² sample area is the minimum acceptable size. (MURR will retain a small portion for our archives.)
A 500-mg fragment is recommended. However, samples as small as 5–10 mg have been analyzed in the past. (We use a trim saw on artifacts to minimize damage to the artifact.)
|Chert||1-g fragment is recommended. 200 mg is the minimum acceptable size. (A diamond saw can be used to remove fragments.)|
1 or 2 g of rock, preferably powdered in advance. Be careful, many grinding procedures will contaminate the sample with iron, cobalt, tantalum, etc. (We will grind for you if necessary for an extra fee.)
250 mg of clean powder obtained by drilling is recommended. Minimum amount is 100 mg.
50 g dry weight with plant roots and insects removed. (The sample will be fired at 700°C before making into powder.)
50 g dry weight with plant roots and insects removed. (Please send clean and dry tempering materials.)
|Obsidian & Chert||
Half-fist to full-fist sized specimens are ideal. (Analytical sample is taken from crushed interior fragments.)